Suppression of Tobacco Mosaic Virus by Bacillus amyloliquefaciens Strain Ba33

Suppression of Tobacco Mosaic Virus (TMV) by B. amyloliquefaciens Ba33 was evaluated on Nicotiana tabacum by spraying before (①), after (②) and simultaneously with (③) TMV inocula. The results suggested that Ba33 treatments reduced local necrotic lesion number and disease index, showing ③ treatment was the best and ① treatment was better than ② treatment in TMV suppression. It also showed Ba33 virus‐contaminated scissors could be disinfected by dipping. Field trials showed that Ba33 had an inhibitory effect of 48.59% in 2009 and 50.54% in 2010, close to the effect of Ningnanmycin, a registered antiviral agent in tobacco. In conclusion, Ba33 might be used as a soil disinfector and an antiviral agent against TMV.     

Interferon gamma does not induce antiviral resistance in T lymphocytes

We compared the activity of human recombinant alpha and gamma interferons (IFNs) on normal T lymphocytes and various T cell lines. IFN gamma, unlike IFN alpha, did not promote the antiviral state in these cells, or induce the activity of 2'-5' oligoadenylate synthetase. The lack of antiviral effect was observed using an RNA virus (VSV) and a DNA virus (HSV, type 1) as challenger viruses.     

Type I interferon promotes cell‐to‐cell spread of Listeria monocytogenes

Type I interferons (IFNs) play a critical role in antiviral immune responses, but can be deleterious to the host during some bacterial infections. Listeria monocytogenes (Lm) induces a type I IFN response by activating cytosolic antiviral surveillance pathways. This is beneficial to the bacteria as mice lacking the type I IFN receptor (IFNAR1^?/?) are resistant to systemic infection by Lm. The mechanisms by which type I IFNs promote Lm infection are unclear. Here, we show that IFNAR1 is required for dissemination of Lm within infection foci in livers of infected mice and for efficient cell‐to‐cell spread in vitro in macrophages. IFNAR1 promotes ActA polarization and actin‐based motility in the cytosol of host cells. Our studies suggest type I IFNs directly impact the intracellular life cycle of Lm and provide new insight into the mechanisms used by bacterial pathogens to exploit the type I IFN response.     

Antiviral Responses in Mouse Embryonic Stem Cells: DIFFERENTIAL DEVELOPMENT OF CELLULAR MECHANISMS IN TYPE I INTERFERON PRODUCTION AND RESPONSE*

We have recently reported that mouse embryonic stem cells (mESCs) are deficient in expressing type I interferons (IFNs) in response to viral infection and synthetic viral RNA analogs (Wang, R., Wang, J., Paul, A. M., Acharya, D., Bai, F., Huang, F., and Guo, Y. L. (2013) J. Biol. Chem. 288, 15926–15936). Here, we report that mESCs are able to respond to type I IFNs, express IFN-stimulated genes, and mediate the antiviral effect of type I IFNs against La Crosse virus and chikungunya virus. The major signaling components in the IFN pathway are expressed in mESCs. Therefore, the basic molecular mechanisms that mediate the effects of type I IFNs are functional in mESCs; however, these mechanisms may not yet be fully developed as mESCs express lower levels of IFN-stimulated genes and display weaker antiviral activity in response to type I IFNs when compared with fibroblasts. Further analysis demonstrated that type I IFNs do not affect the stem cell state of mESCs. We conclude that mESCs are deficient in type I IFN expression, but they can respond to and mediate the cellular effects of type I IFNs. These findings represent unique and uncharacterized properties of mESCs and are important for understanding innate immunity development and ESC physiology.     

Crystal structure of Zebrafish interferons I and II reveals conservation of type I interferon structure in vertebrates

Interferons (IFNs) play a major role in orchestrating the innate immune response toward viruses in vertebrates, and their defining characteristic is their ability to induce an antiviral state in responsive cells. Interferons have been reported in a multitude of species, from bony fish to mammals. However, our current knowledge about the molecular function of fish IFNs as well as their evolutionary relationship to tetrapod IFNs is limited. Here we establish the three-dimensional (3D) structure of zebrafish IFN?1 and IFN?2 by crystallography. These high-resolution structures offer the first structural insight into fish cytokines. Tetrapods possess two types of IFNs that play an immediate antiviral role: type I IFNs (e.g., alpha interferon [IFN-α] and beta interferon [IFN-β]) and type III IFNs (lambda interferon [IFN-λ]), and each type is characterized by its specific receptor usage. Similarly, two groups of antiviral IFNs with distinct receptors exist in fish, including zebrafish. IFN?1 and IFN?2 represent group I and group II IFNs, respectively. Nevertheless, both structures reported here reveal a characteristic type I IFN architecture with a straight F helix, as opposed to the remaining class II cytokines, including IFN-λ, where helix F contains a characteristic bend. Phylogenetic trees derived from structure-guided multiple alignments confirmed that both groups of fish IFNs are evolutionarily closer to type I than to type III tetrapod IFNs. Thus, these fish IFNs belong to the type I IFN family. Our results also imply that a dual antiviral IFN system has arisen twice during vertebrate evolution.     

Synthesis,antiviral activity,and molecular docking study of trans-ferulic acid derivatives containing acylhydrazone moiety

In this study, we report the synthesis and antiviral activity of trans-ferulic acid derivatives containing acylhydrazone moiety. Biological tests demonstrated that most target compounds showed potent antiviral activity against tobacco mosaic virus (TMV). Compound D4 showed remarkable inactivating activity with EC₅₀ value of 36.59 μg/mL, which was obviously superior to ribavirin (126.05 μg/mL). Molecular docking results revealed that compound D4 exhibited the optimal combining capacity with five hydrogen bonds to different amino-acid residues of TMV coat protein (TMV-CP). Docking results were consistent with the inactivating activity of target compounds against TMV.     

Cloning,expression, and purification of an antiviral protein from Pseudomonas fluorescens CZ and its antagonistic activity against tobacco mosaic virus

The antiviral alkaline phosphatase L (AapL) protein of Pseudomonas fluorescens CZ was expressed in Escherichia coli, purified using the Ni-NTA column, and its antiviral activity against tobacco mosaic virus (TMV)-infected Nicotiana was tested. The recombinant protein (360?µg/mL) showed stability and most effective suppression in vitro (94.85%) against TMV.     

Inhibitory effect of fucoidan from brown alga Fucus evanescens on the spread of infection induced by tobacco mosaic virus in tobacco leaves of two cultivars

The effect of fucoidan from the brown alga Fucus evanescens on the spread of infection induced by tobacco mosaic virus (TMV) was investigated in the leaves of tobacco (Nicotiana tabacum L.) of two cultivars (Ksanti-nk and Samsun). In the leaves of cv. Ksanti-nk inoculated with a mixture of TMV preparation (2 μg/ml) and fucoidan (1 mg/ml), the number of local necrotic lesions induced by the virus decreased by more than 90% as compared with the leaves inoculated with the virus alone. In tobacco leaves of cv. Samsun, virulence and the concentration of the virus 3 days after inoculation with the same mixture of TMV and fucoidan were by 62 and 66%, respectively, lower than in the leaves inoculated with TMV alone. As the infection spread, the inhibitory effect of fucoidan decreased. When the leaves were treated with fucoidan before and after the inoculation with TMV, its antiviral activity was less pronounced than when a mixture of the virus and the polysaccharide was used as inoculum. Electron microscopic investigation of TMV mixed with fucoidan often showed agglutinated virions. The highest virulence of the mixture (TMV preparation, 12 μg/ml, plus fucoidan, 1 mg/ml) was observed upon its twofold dilution, and after that it decreased. It was concluded that, when the leaves were inoculated with the mixture of TMV and fucoidan, the latter affected not only the plant but the virus as well. Treatment of tobacco leaves, cv. Ksanti-nk, with actinomycin D (10 μg/ml) 24 h before the inoculation with TMV almost completely suppressed the effect of fucoidan, indicating that fucoidan acted at a gene level.     

The zinc finger antiviral protein acts synergistically with an interferon-induced factor for maximal activity against alphaviruses

Type I interferons (IFNs) signal through specific receptors to mediate expression of genes, which together confer a cellular antiviral state. Overexpression of the zinc finger antiviral protein (ZAP) imparts a cellular antiviral state against Retroviridae, Togaviridae, and Filoviridae virus family members. Since ZAP expression is induced by IFN, we utilized Sindbis virus (SINV) to investigate the role of other IFN-induced factors in ZAP's inhibitory potential. Overexpressed ZAP did not inhibit virion production or SINV-induced cell death in BHK cells deficient in IFN production (and thus IFN signaling), suggesting a role for an IFN-induced factor in ZAP's activity. IFN pretreatment in the presence of ZAP resulted in greater inhibition than IFN alone. Using mouse embryo fibroblast (MEF) cells deficient in Stat1, we showed that signaling through the IFN receptor is necessary for IFN′s enhancement of ZAP activity. Unlike in BHK cells, however, overexpressed ZAP exhibited antiviral activity in the absence of IFN. In wild-type MEFs with an intact Stat1 gene, IFN pretreatment synergized with ZAP to generate a potent antiviral response. Despite failing to inhibit SINV virion production and virus-induced cell death in BHK cells, ZAP inhibited translation of the incoming viral RNA. IFN pretreatment synergized with ZAP to further block protein expression from the incoming viral genome. We further show that silencing of IFN-induced ZAP reduces IFN efficacy. Our findings demonstrate that ZAP can synergize with another IFN-induced factor(s) for maximal antiviral activity and that ZAP's intrinsic antiviral activity on virion production and cell survival can have cell-type-specific outcomes.     

Herpesviruses and the Type III Interferon System

Type III interferons (IFNs) represent the most recently discovered group of IFNs. Together with type I IFNs (e.g. IFN-α/β), type III IFNs (IFN-λ) are produced as part of the innate immune response to virus infection, and elicit an anti-viral state by inducing expression of interferon stimulated genes (ISGs). It was initially thought that type I IFNs and type III IFNs perform largely redundant functions. However, it has become evident that type III IFNs particularly play a major role in antiviral protection of mucosal epithelial barriers, thereby serving an important role in the first-line defense against virus infection and invasion at contact areas with the outside world, versus the generally more broad, potent and systemic antiviral effects of type I IFNs. Herpesviruseses are large DNA viruses, which enter their host via mucosal surfaces and establish lifelong, latent infections. Despite the importance of mucosal epithelial cells in the pathogenesis of herpesviruses, our current knowledge on the interaction of herpesviruses with type III IFN is limited and largely restricted to studies on the alphaherpesvirus herpes simplex virus (HSV). This review summarizes the current understanding about the role of IFN-λ in the immune response against herpesvirus infections.     

Targeted Induction of Interferon-λ in Humanized Chimeric Mouse Liver Abrogates Hepatotropic Virus Infection

Background & Aims

The interferon (IFN) system plays a critical role in innate antiviral response. We presume that targeted induction of IFN in human liver shows robust antiviral effects on hepatitis C virus (HCV) and hepatitis B virus (HBV).

Methods

This study used chimeric mice harboring humanized livers and infected with HCV or HBV. This mouse model permitted simultaneous analysis of immune responses by human and mouse hepatocytes in the same liver and exploration of the mechanism of antiviral effect against these viruses. Targeted expression of IFN was induced by treating the animals with a complex comprising a hepatotropic cationic liposome and a synthetic double-stranded RNA analog, pIC (LIC-pIC). Viral replication, IFN gene expression, IFN protein production, and IFN antiviral activity were analyzed (for type I, II and III IFNs) in the livers and sera of these humanized chimeric mice.

Results

Following treatment with LIC-pIC, the humanized livers of chimeric mice exhibited increased expression (at the mRNA and protein level) of human IFN-λs, resulting in strong antiviral effect on HBV and HCV. Similar increases were not seen for human IFN-α or IFN-β in these animals. Strong induction of IFN-λs by LIC-pIC occurred only in human hepatocytes, and not in mouse hepatocytes nor in human cell lines derived from other (non-hepatic) tissues. LIC-pIC-induced IFN-λ production was mediated by the immune sensor adaptor molecules mitochondrial antiviral signaling protein (MAVS) and Toll/IL-1R domain-containing adaptor molecule-1 (TICAM-1), suggesting dual recognition of LIC-pIC by both sensor adaptor pathways.

Conclusions

These findings demonstrate that the expression and function of various IFNs differ depending on the animal species and tissues under investigation. Chimeric mice harboring humanized livers demonstrate that IFN-λs play an important role in the defense against human hepatic virus infection.     

Influence of κ/β-carrageenan from red alga <Emphasis Type="Italic">Tichocarpus crinitus</Emphasis> on development of local infection induced by tobacco mosaic virus in Xanthi-nc tobacco leaves

The influence of κ/β-carrageenan from red marine alga Tichocarpus crinitus on the development of tobacco mosaic virus (TMV) infection in Xanthi-nc tobacco leaves was studied. It was shown that the number of necrotic lesions on the leaves inoculated with the mixture of TMV (2 μg/ml) and carrageenan (1 mg/ml) was reduced by 87%, compared to the leaves inoculated with the virus only. The suppression of virus infection was also observed when leaves were treated with carrageenan 24 h before or 24 h after leaf inoculation with TMV; however, in these cases, suppression was less evident than after inoculation with the virus-polysaccharide mixture. It is supposed that the antiviral activity of carrageenan applied together with TMV may be explained by its action not only on the plant but also on the virus itself. The inhibitory effect of carrageenan pretreatment can be explained by its favorable effect on tissue resistance to infection. The suppression of this resistance by actinomycin D indicates that carrageenan functions via its action on the cell genome.     

Amino acid differences in interferon-tau (IFN-τ) of Bos taurus Coreanae and Holstein

Interferons (IFNs) are commonly grouped into type I and type II IFN. Type I IFNs are known as antiviral IFNs including IFN-α, IFN-β, and IFN-ω whereas type II IFN is referred to immune IFN and IFN-γ is only member of the type II IFN. Type I IFNs are induced by virus invading however type II IFN is produced by mitogenic or antigenic stimuli. IFN-τ was first identified in ruminant ungulates as a pregnancy recognition hormone, trophoblastin. IFN-τ constitutes a new class of type I IFN, which possesses the common features of type I IFN, such as the ability to prevent viral infection and to limit cell proliferation. In addition, IFN-τ is unique in that it is induced by pregnancy unlike other type I IFNs. We cloned Bos taurus (B. T.) Coreanae IFN-τ from peripheral blood mononuclear cells. The amino acid sequence of B. T. Coreanae IFN-τ shares only 90.3% identity with that of Holstein dairy cow. Recombinant B. T. Coreanae and Holstein IFN-τ proteins were expressed in Escherichia coli and the antiviral activity of IFN-τ proteins were examined. Both recombinant proteins were active and protected human WISH and bovine MDBK cells from the cytopathic effect of vesicular stomatitis virus. The recombinant IFN-τ protein of B. T. Coreanae and Holstein properly induced the expression of antiviral genes including 2',5'-oligoadenylate synthetase (OAS) and Mx GTPase 1 (Mx-1).     

Retinoic acid or methionine enhance interferon's inhibition of the transformed phenotype with no effect on tumorigenicity

Retinoic acid (RA) and methionine were studied for their relative effectiveness in enhancing the ability of interferons (IFNs) to reverse the phenotype of murine methylcholanthrene (MCA)-transformed cells and human osteosarcoma (OHA) cells. Treatment with RA (1 microM) and methionine (25mM) alone had minimal or no effect on the proliferation of MCA and OHA cells or on the ability to form tumors in animals. Combination of these two agents with IFNs however, potentiated the inhibitory effects of IFNs on proliferation and colony formation of MCA transformed cells but not on their tumorigenicity. Similarly in human tumor OHA cells, only the combination of IFN and RA was more effective than IFN alone on proliferation and colony formation but not on tumorigenicity. Thus, the enhanced effects of combined treatments on cell proliferation in vitro could be distinguished from the inhibitory effects of IFNs on tumorigenicity in both murine transformed cells and human tumor cells.     

Toll-Like Receptor Expression and Induction of Type I and Type III Interferons in Primary Airway Epithelial Cells

Interferons (IFNs) are a critical component of the first line of antiviral defense. The activation of Toll-like receptors (TLRs) expressed by dendritic cells triggers different signaling cascades that result in the production of large amounts of IFNs. However, the functional consequences of TLR activation and differential IFN production in specific cell populations other than antigen-presenting cells have not yet been fully elucidated. In this study, we investigated TLR expression and polarization in airway epithelial cells (AECs) and the consequences of TLR agonist stimulation for the production of type I (IFN-α/β) and type III (IFN-λ) IFNs. Our results show that the pattern of expression and polarization of all TLRs in primary AEC cultures mirrors that of the human airways ex vivo and is receptor specific. The antiviral TLRs (TLR3, TLR7, and TLR9) are mostly expressed on the apical cell surfaces of epithelial cells in the human trachea and in primary polarized AECs. Type III IFN is the predominant IFN produced by the airway epithelium, and TLR3 is the only TLR that mediates IFN production by AECs, while all TLR agonists tested are capable of inducing AEC activation and interleukin-8 production. In response to influenza virus infection, AECs can produce IFN-λ in an IFNAR- and STAT1-independent manner. Our results emphasize the importance of using primary well-differentiated AECs to study TLR and antiviral responses and provide further insight into the regulation of IFN production during the antiviral response of the lung epithelium.     

Mechanism of interferon action. Kinetics of induction of the antiviral state and protein phosphorylation in mouse fibroblasts treated with natural and cloned interferons

The induction of phosphorylation of both protein P1 and protein synthesis initiation factor eIF-2 alpha and the inhibition of virus replication were examined in mouse L929 fibroblasts treated with either natural mouse or individual cloned human interferons (IFN). Natural mouse IFN synthesized in Newcastle disease virus-induced L929 cells and two cloned human leukocyte IFN subspecies synthesized in Escherichia coli, IFN-alpha D and IFN-alpha A/D, possessed antiviral activity in L929 cells as measured by single cycle virus yield reduction with both vesicular stomatitis virus and reovirus. Natural L929 IFN and cloned IFNs, alpha D and alpha A/D, also induced the protein kinase that catalyzed the phosphorylation of endogenous ribosome-associated protein P1 and the alpha subunit of purified initiation factor eIF-2. Two other cloned human IFNs, alpha A and alpha D/A, were poor inducers of both the antiviral state and the phosphorylation of P1 and eIF-2 alpha in mouse L929 cells. The ability of individual human IFN-alpha subspecies to induce P1 and eIF-2 alpha phosphorylation in mouse L929 cells correlated with their ability to induce an antiviral state. Furthermore, the detailed kinetics of induction, in mouse L929 cells, of P1 and eIF-2 alpha phosphorylation and of the antiviral state by the heterologous cloned human IFN-alpha A/D were equivalent to the kinetics of induction by the homologous natural mouse L929 IFN. These results suggest that different subspecies of biologically active IFN induce equivalent antiviral activities and biochemical changes in mouse L929 cells, and that protein phosphorylation may play a major role in the antiviral mechanism of IFN action in mouse L929 fibroblasts.     

Regulation of apoptosis by type III interferons

Abstract. Objective: Two types of interferons (IFNs), type I (IFN‐α/β) and type III (IFN‐λs), utilize distinct receptor complexes to induce similar signalling and biological activities, including recently demonstrated for IFN‐λs antitumour activity. However, ability of type III IFNs to regulate cell population growth remains largely uncharacterized.Materials and methods: Intact and modified human colorectal adenocarcinoma HT29 cells were used to study regulation of apoptosis by IFN‐λs. Results and Conclusions: We report that the IFN‐λR1 chain of the type III IFN receptor complex possesses an intrinsic ability to trigger apoptosis in cells. Signalling induced through the intracellular domain of IFN‐λR1 resulted in G₁/G₀ phase cell cycle arrest, phosphatidylserine surfacing and chromosomal DNA fragmentation. Caspase‐3, caspase‐8 and caspase‐9 were activated; however, pancaspase inhibitor Z‐VAD‐FMK did not prevent apoptosis. In addition, the extent of apoptosis correlated with the level of receptor expression and was associated with prolonged IFN‐λ signalling. We also demonstrated that the ability to trigger apoptosis is a unique intrinsic function of all IFN receptors. However, more robust apoptosis was induced by signalling through type III IFN receptor than through type I or type II (IFN‐γ) receptors, suggesting higher cytotoxic potential of type III IFNs. In addition, we observed that IFN‐γ treatment sensitized HT29 cells to IFN‐λ‐mediated apoptosis. These results provide evidence that type III IFNs, alone or in combination with other stimuli, have the potential to induce apoptosis.     

干扰素抗病毒效力影响因素的研究进展

干扰素（interferons,IFN）是一类重要的细胞因子,具有多种抗病毒和免疫调节等作用。根据其结构特点、受体、细胞来源和生物学活性,可分为Ⅰ型、Ⅱ型和Ⅲ型。IFN通过与其特异性受体结合,通过一个复杂且部分重叠的基因转录过程来发挥作用,其核苷酸多态性和基因突变可影响IFN反应及对病毒感染的敏感性。几乎所有的病毒都有抵抗IFN抗病毒活性的机制和效力,包括直接影响IFN产生和影响下游效应因子。不同型别IFN在行使抗病毒或免疫调节功能时具有拮抗或协同作用。本文就IFN基因变异、病毒抗IFN策略及IFN之间的协同/拮抗作用进行综述,以期能更好地理解IFN的抗病毒作用。     

Human T-lymphoblastoid cell lines with high and low abilities to produce interferon-gamma constitutively and their susceptibilities to interferon

A human T-lymphoblastoid cell line, TCL-Fuj, produces large amounts of interferon (IFN)-gamma constitutively. A variant cell line, 2M, was derived from it. Both cell lines express similar surface antigen markers, but differ in surface morphology. Compared with the parent TCL-Fuj cell line, 2M produced less IFN-gamma constitutively but more in response to IFN inducers. The IFNs produced constitutively and on stimulation with inducers were analyzed by SDS-polyacrylamide gel electrophoresis. In TCL-Fuj cells, the constitutive and induced IFNs consisted of the same molecular species (22K and 39K). In 2M cells, smaller IFNs were produced constitutively (18K and 32K) and induction resulted in a marked increase of 22K molecules. These two cell lines also differed in sensitivity to the antiviral activity of IFN. Other T-lymphoblastoid cell lines, HPB-ALL and TCL-Fuj 4 cells, which did not produce IFN-gamma were permissive for vesicular stomatitis virus (VSV) replication; its growth was markedly suppressed by IFN-gamma and -alpha. TCL-Fuj cells were also permissive for VSV, but were not susceptible to the antiviral effect of the IFNs. In contrast, in 2M cells the multiplication of VSV was restricted; the viral yield was further reduced by the IFNs and increased by treatment with anti-human IFN-gamma serum. Several clonal cell lines derived from TCL-Fuj and 2M cells had characteristics similar to the respective parent cell lines. The growth of both cell lines was not affected by IFN-gamma or by -alpha. The separation of antiviral and anti-proliferative susceptibilities was peculiar to 2M cells unlike other cell lines.     

Apoptosis and interferons: role of interferon-stimulated genes as mediators of apoptosis

IFNs are a family of cytokines with pleiotropic biological effects mediated by scores of responsive genes. IFNs were the first human proteins to be effective in cancer therapy and were among the first recombinant DNA products to be used clinically. Both quality and quantity of life has been improved in response to IFNs in various malignancies. Despite its beneficial effects, unraveling the mechanisms of the anti-tumor effects of IFN has proven to be a complex task. IFNs may mediate anti-tumor effects either indirectly by modulating immunomodulatory and anti-angiogenic responses or by directly affecting proliferation or cellular differentiation of tumor cells. Both direct or indirect effects of IFNs result from induction of a subset of genes, called IFN stimulated genes (ISGs). In addition to the ISGs implicated in anti-viral, anti-angiogenic, immunomodulatory and cell cycle inhibitory effects, oligonucleotide microarray studies have identified ISGs with apoptotic functions. These include TNF- related apoptosis inducing ligand (TRAIL/Apo2L), Fas/FasL, XIAP associated factor-1 (XAF-1), caspase-4, caspase-8, dsRNA activated protein kinase (PKR), 2'5'A oligoadenylate synthetase (OAS), death activating protein kinases (DAP kinase), phospholipid scramblase, galectin 9, IFN regulatory factors (IRFs), promyelocytic leukemia gene (PML) and regulators of IFN induced death (RIDs). In vitro IFN-, IFN- and IFN- induced apoptosis in multiple cell lines of varied histologies. This review will emphasize possible mechanisms and the role of ISGs involved in mediating apoptotic function of IFNs.